Method of annealing steel or iron products



, 1925 2 Sheets-Sheet l Qooooooo H. W. IRWIN METHOD OF ANNEALING STEEL OR IRON PRODUCTS Filed Aug.

Sept. 1, 1925A /W/rwin.

c @wf arf/M 2 Sheets-Sheet 2 H. W. IRWIN |II'. IIIIIIII' l l Filed 1mg.V 13. 1923 MTHOD QF ANNEAL-NG STEEL OR IRON PRODUCTS :E: l* R i Sept. l, 1925.

Patented Sept'. 1, 1925.

UNITED 5STATES HARRY W. IRWIN, or CANTON, omo.

METHOD OF ANNEALING STEEL OR IRON PRODUCTS.

Applicationmea August 1a, 1923. serial No. 657,085.

To all whom it may oon-cern.'

Be it known that I, HARRY W. InwrN, a citizen of the United States, residing at Canton, in the county of Stark and State of Ohio, have invented a new and Improved Method of Annealing Steel or Iron Products, of which the following is a specification.

The invention relates to the heat treatment of iron or steel sheets, or the like, for the purpose 'of annealing the same; and the object of the improvement is to cool a pack of sheets which have been heated to an annealing temperatureA in an ordinary annealing box in such a manner that they will be uniformly annealed throughout their extent.

A further object or result of the improved method is to increase the productive capacity and reduce the expense of maintenance of the annealing furnace used for heating the sheets, thereby reducing the cost of the annealing process as a whole. l

A well kown method of annealing is to enclose a pack of sheets, o-r other iron or steel products, in an annealing box, and to heat the same in a furnace to a temperature of say, from some 1600Q to 2200o F.; and after maintaining the same at an annealing heat for several hours, to cool the furnace by opening itspdoors as rapidly as may be possible unt-il the annealing box and its contents can be removed from the furnace, after which the cooling of the same is continued in the open; and in so doing it has been found practicallyT impossible to cool the box and its contents so gradually as to produce a uniformity in the annealing of the several sheets and in the different parts of the same sheet.

Furthermore, the time required for cooling the annealing box and its contents before it can be safely removed from a furnace for being cooled in the open, not only prevents the use of the furnace for heating another f charge, but also requires the furnace to be reheated for another charge to the extent it has been cooled for the previous charge, with the attendant damage to the furnace resulting from a frequent heating and reheating thereof for successive annealing operations.

These dificulties are overcome by the improved process by removing the annealing box and its contents from the furnace 'after it has been raised to and maintained at an annealing temperature therein for some three or four hours, after which the annealing box and its contents intact are immediately enclosed in an inverted box or hood so as to form an air chamber between the hood and box and protect the box from being suddenly cooled by air currents at any place and prevent a sudden cooling of any portion of its contents.

The hood. employed for carrying out the improved process may be made with astruc' tural steel frame and hollow tiled walls laid to form longitudinal air passages opening only into upright flues atthe corners of the side Walls and of the arched ues at the ends of the top wall, so as to provide an additional air chamber in the wall of the hood, which serves further to prevent a sudden cooling of any part of the annealing box and its contents when covered by the hood.

The improved method may be carried out by the apparatus illustrated in the accompanying drawings, in which- Figure 1 is a longitudinal section of an annealing furnace with an annealing box therein partly broken away to show a pack of sheetswithin the box;

Fig. 2, a side elevation partly broken away of a cooling hood with an annealing box containing a pack of sheets therein;

Fig. 3, a cross section of the same, as on line 3--3, Fig. 2;

Fig. 4, a side elevation of the improved cooling hood;

Fig. 5, an end elevation of the same;

Fig. 6, a plan section of the same, on line 6-6, Figs. 4. and 5; and

Fig. 7, a cross section of the hood, on line 7-7, Figs. 4 and 6.

Similar numerals refer to similar parts throughout the drawings.

A pack of sheets 8 or the like may be heated for annealing in an ordinary annealing box 9 inverted upon a bottom plate 10 having a rim 11 for sealing with sand 12 in the usual manner; and the bottom plate may ride upon a carriage 13 traveling on rolls 14, riding in ways 15 and 15 for moving into and out of the furnace.

The furnace is heated unt-il the annealing box and its contents have been brought to an annealing temperature of from some 1600 to 2200o F., and may be maintained at this temperature for a period of three or four hours as desired. l

The annealing box with its contents is then removed from the furnace without any preliminary cooling, andis then completely covered by a hood 16 inverted over the annealing box and its bottom plate, so as to completely enclose the same, exce ting only the lower surface of the bottom p ate.

In ordinary practice, the annealing box may be placed upon cross rails 17, and the rim of the hood may rest upon the same rails with a slight clearance 18, of say two inches between the rim of the hood and the side and end edges of the bottom plate. The chamber 19 thus formed between. the walls of the 4 hood and the walls of the annealing box, forms a substantially quiescent air space whichv insulates the annealing box from atmospheric currents and prevents the annealing box and its contents from cooling any faster than the contained heat is conveyed by conduction through the air contained. in the chamber to the walls of the hood.

It is preferred to construct the hood with Walls of hollow tile 20 laid in longitudinal rows within a structural steel frame which ma y include channel sills 21 and 22 along each side and end with boiler plate sidewalls 23 and end walls 24 outside the tile walls, and upright angles 25 and 26 at the outer and inner side of each corner. Intermediate the ends in each side may be provided upright channels 27 placed back to back rising from the channel sill and upright flat bands 28 on the outer and inner sides thereof. At the top of each side wall, the boiler plate is preferably bent inward over the top of the hollow tile walls, and may then be arched between the side walls to form a centering 29 for the hollow tiles 20 laid in longitudinal rows to form an arched top for the hood. Z-bar sills 30 connected by tie rods 30 may be provided to form haunches for the hollow tile arch, and at each end the frame may be tied together by arched plates 31, with strap bails 32 on each end and strap bars 33 on each side by means of which the hood,

may be lifted by the hooks of a traveling crane for placing the same over and removinU it from an -annealing box.

he hollow tile are laid in longitudinal rows along each side and end of the box and also along the arched roof thereof, so as to form series of independent air channels 34 opening only into upright iues 35 at the corners of the hood, thereby forming substantially dead air spaces through which heat can only pass by conduction through the wall of the hood; and similar lues 35 may be formed at the ends of the arch 'top tiles by an arched flange 36 at each end of the top, from which an outlet opening or lue 37 may be controlled by a damper 38.

In this manner the initial heat carried by the annealing box and its contents when it is removed from the furnace may be retained therein for a considerable period, of say from three to four hours, before there is any material cooling thereof so that the an- Dealing process may be continued for that length of time after the annealing box has been removed from the furnace; and thereafter the cooling of the annealing box will continue so gradually, during an extended period, that the contents of the box will be maintained at substantially the same heat throughout and will be uniformly annealed at the completion when completely cooled; after which the hood and the annealing box may -be removed and the sheets or other product removed from the bottom plate.

It is evident that the annealing/oven is ready for another charge just as soon as one annealing box has been removed therefrom, and as the temperature of the furnace has not been reduced prior to the removal of the one annealing box, it does not need to be reheated before the next 'box can be raised to an annealing temperature.

I claim:

1. The method lof annealing iron or steel products and the like, which consists in placing the same in an annealing box and heating them in a furnace to an annealing temperature, then removing the box with its contents therein from the furnace and placing a covering hood over the top and around the sides only of the box forming an air chamber between the box and the hood.

2. The method of annealing iron or steel products and the like, which consists in placing the same in an annealing box and heating them in a furnace to an annealing temperature, then removing the box with its contents therein from the furnace and placing a covering hood having independent air channels in its walls over the top and around the sides only of the box and forming in air chamber between the box and the hoo 3. The method of annealing iron or steel products and the like, which consists in placing the same in an annealing box and heating them in a furnace to an annealing temperature and maintaining the same for several hours, then removing the box with its contents therein from the furnace and placing a covering hood over the top and around the sides only of the box forming a quiescent air chamber between the box and the hood, until the box and its contents are cooled, and then removing the hood and the box.

4. Apparatus for annealing iron and steel products and the like including an annealing box and a removable hood covering the top and sides only of the annealing box forming an air chamber between the box and the hood.

5. Apparatus for annealing iron and steel products and the like including an annealing box and a hood covering the annealing box forming an air chamber between the box and the hood, there being independent air channels in the walls of the hood.

6. Apparatus for annealing iron and steel products and the like including an ang healing box and a hood covering the annealing box forming an air chamber between the box and the hood, there being flues in the corners of the hood and inde-pendent air channels in its Walls opening into the lues.

7. Apparatus for annealing iron and steel products and the like including an annealing box and a hood covering the annealing box forming an air chamber between the box and the hood, there being ues in the corners of the hood'and independent air channels in its Walls opening into the flues, and damper controlled outlets from the flues.

,HARRY W. IRWIN. 

